The method of the invention may be used whenever servo-control is inserted in electrical chopper structures for the purpose of regulating a parameter. Applications of the invention, extend, in particular, to space applications, aviation applications, and consumer applications.
The method of the invention is a method of controlling chopper regulators in particular on the basis of a bidirectional peak current controlled modulator and of a stabilizing control by state feedback.
To obtain dynamic performance compatible with that of DC amplifiers while implementing high power levels (a few watts to several kW) at high energy efficiency (greater than 85%), chopper regulators and amplifiers must combine:
a high synchronization frequency (a few fractions of a MHz to several MHz); and
large signal servo-control with a passband which is close as possible to one-half the sampling frequency.
At present, two techniques are in competition:
non-linear analog stabilizing control by feeding back the prior states of the various possible states of the system; and
digital control with prior storage of the various possible states of the system in a memory.
Stabilizing control by state feedback may be performed by a self-adaptive feedback loop such as that described in an article by G. Salut, J. C. Marpinard and M. Valentin entitled: "Large signal feedback control for power switching conversion" (PESC 1985, Toulouse).
In the context of a buck chopper voltage regulator, this feedback loop implements:
two linear amplifiers; PA1 a summing circuit; and PA1 a non-linear function divider (a non-linear pulse width modulation (PWM) modulator for transforming an analog magnitude into a duration in time with a given clock). PA1 seven linear amplifiers; PA1 two dividers and a non-linear multiplier; PA1 a summing circuit; and PA1 a non-linear PWM modulator. PA1 three amplifiers; PA1 a summing circuit; and PA1 a non-linear PWM modulator. PA1 the input energy source is voltage limited (a set of batteries, a solar panel, a distribution network); PA1 the output voltage is generally the parameter that is servo-controlled and thus limited in amplitude; and PA1 the energy in transit is controlled by measuring pulse current.
With a boost regulator, the following are used:
As described in an article by A. Capel, J. C. Marpinard, G. Salut, M. Valentin and D. O'Sullivan entitled "A bidirectional high power cell using large signal feedback control with maximum conduction control for space applications" (ESA Journal, 1986, Vol. 10) a possible simplification lies in the fact that information previously collected from the middle of the power circuit in the inductor L and the load R can be combined at the current through the capacitor C, while the PWM modulator may be biased by the input voltage V, thereby making it possible to eliminate the non-linear function divider.
The control unit is then reduced to:
It may be observed that the current sensors in all of these systems are unsuitable for providing protection against short circuits in the regulator or in its load.
An object of the invention is to solve this problem.